Abstract Detail

Paleobotanical Section

Baresch, Andrés [1], Jaramillo, Carlos [2], Madriñán, Santiago [1].

Character variation in Miconia (Melastomataceae) at two altitudinal gradients of the Eastern Cordillera (Colombian Andes) and its potential for paleoaltimetry.

Methods for the estimation of paleoelevation have been proposed based on change of stomatal characters responding to changes in CO₂ partial pressure. Until now no study has been carried applying this technique for species present in the tropics. Additionally measurements of paleoelevations in the Northern Andes are scarce and based on a technique with low resolution (nearest relative method). The presence of leaf macrofossils on localities tracking the rise of the Andes and the need for various approaches to estimate accurately paleoelevation justifies a study evaluating this new techniques for tropical plants.
The genus Miconia (Melastomataceae) has a broad neotropical distribution, occurring on most ecosystems, beeing predominant on secondary forests. Specimens of Melastomataceae have been reported on fossil localities tracking the rise of the Northern Andes. The objective of this study is to evaluate stomatal characters of Miconia species for correlations with elevation and its potential for paleoaltimetric studies.
Sun leaves of 29 individuals belonging to 7 species were collected on stations ranging from 200 to 2500 m elevation, at the Western and Eastern Slopes of the Eastern Cordillera of the Northern Andes. Stomatal density index and stomatal length were measured. Additionally climatic data were obtained for each locality.
This study shows that neither stomatal density nor index correlate with elevation. Stomatal length increased with elevation but is highly linked to stomatal density. Due to this association, an index of potential conductance encompassing both terms was calculated. This index is highly correlated with elevation (R²=0.65) when leaves smaller than 23 cm² are analyzed. When leaves of all sizes are considered the correlation decreases due to a tendency of greater index on small leaves compared to bigger ones. An application of the best-fitted correlation to predict elevation yields an uncertainty of +/- 520, improving the accuracy of the nearest relative method.
Due to the lack of data is not possible to establish a climactical or atmospheric condition responsible for our results.

Broader Impacts:

Related Links:
Laboratorio de Botánica y Sistemática

1 - Universidad de los Andes, Departamento de Ciencias Biológicas, Laboratorio de Botánica y Sistemática, Apartado Aéreo 4976, Bogotá, DC, Colombia
2 - Center for Tropical Paleoecology and Archeology, Smithsonian Tropical Research Institute, Box 0843-03092 & # 8232, Balboa, Ancon, 34002-0948, Republic of Panama

Keywords:
Paleoelevation
Paleoaltimetry
Stomatal length
stomatal density
Miconia
Potential conductance index .

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM
Number: PPB003
Abstract ID:195